If you are into Wolf/Steel Casing...There have been some great deals on AIMSurplus lately for 9MM...these go for about 22 cents a round. Once the deal posts, it doesn't last long though. Had some earlier this morning, that I almost picked up at those prices. WPA (Wolf) 9mm 115grn FMJ 50rd Box
Also, I have seen .223 there for about 30 cents a round. Both are sold out now, but they have come back up at least once a day from what I have seen. WPA (Wolf) .223 55grn FMJ 20rd Box
I've seen a few "okay for this stupid craziness" deals on Gunbroker for 5.7x28. I've been searching high and low and been coming up dry on 5.7, unless I was willing to spend $1.50 a round (no fricking way). The 5.7 shortage has been so bad, I've almost bought an FN FiveSeven pistol a couple of times because those particular deals came with 500 rounds of ammo.
However, the price is coming down. You can find some American Eagle for around $30 per box (it was about $20 to $25 pre-crazy). Here is a link to one on Gunbroker for 1000 rounds of American Eagle for $600 with $25 shipping.
I finally broke down and bought a 1000, as I've had my PS90 for the better part of a year and only had 4 boxes to put through it (and I'm ashamed to say what I paid for those boxes in a moment of weakness at the 1500). I've had 2000 rounds on order from FiveSevenAmmo.com at a reasonable price for about 7 months now, but they are infinitely backordered and only tell me "We don't know" when I ask when they are expecting the ammo in.
The Martinsville LGS bought 5k thunderbolts from a local for 4.50/box. They sell for 4.75 no tax. 1 box limit... Desperate locals can have a few rounds.